Apparatus and process for the measurement of the pressure of corrosive material

ABSTRACT

Apparatus for subjecting a corrosive material to a controlled pressure comprises a pressure vessel and a pressure measurement chamber, separated by a flexible diaphragm, which keeps the corrosive material within the pressure vessel, yet allows pressure to be transmitted to the pressure measurement chamber for measurement. Two methods of maintaining the flexible diaphragm in a pressure-transmissive position are described.

@tts l tt Harding et allu [451 ,lan, 1,1972

APPARATUS AND PWUCfi FUR THE MlEAS v Inventors: W R. Harding, StateCollege, Pa;

Vincent G. Hill, Kingston, Jamaica Assignee: The Ctirborundum (Zompmiy,Niagara Falls, NY.

Filed: Dec. 2, 1969 Appl. No.: ssmm US. Cl ..73/395, 73/406 lint. Cl...G01ll 7/08 lField of Search ....73/395, 152, 406

[56] References Cited! UNITED STATES PATENTS 2,284,707 5/1942 Wilson..73/395 X 2,883,995 4/1959 Bialous et a1. 3,350,931 11/1967 Johnson etal Primary ExaminerDonald O. Woodie] Altorney-K. W. Brownell [5 7]ABSTRACT Apparatus for subjecting a corrosive material to a controlledpressure comprises a pressure vessel and a pressure measurement chamber,separated by a flexible diaphragm, which keeps the corrosive materialwithin the pressure vessel, yet allows pressure to be transmitted to thepressure measurement chamber for measurement. Two methods of maintainingthe flexible diaphragm in a pressure-transmissive position aredescribed.

3 Claims, 3 Drawing Figures PATENIED m I 8 I972 M B .2 H m U N 0 r\ FIG.I

ATTORN EY APPARATUS AND lPlltGiClEdS FOR THE MEASUREMENT OF TillillPRESSURE Gil CGlhlltOblll/E Mh'lllllitlAL BACKGROUND OF THE IINVENTIONThis invention relates to apparatus and a process for the measurement ofthe pressure of corrosive material.

Numerous physical or chemical changes require high pressures, andfrequently also high temperatures, for their accomplishment. Many ofthese changes require or proceed more expeditiously using corrosivesolutions as well, for example the hydrothermal growth of variouscrystals such as potassium tantalate/niobate (D. J. Marshall and R. A.Laudise, pages 557-tl in Crystal Growth, H. S. Peiser, ed., PergamonPress, inc, 1967 beryllium oxide (V. G. Hill and R. I. l-larker, J.Electrochem. Soc. 115, 294-98) and rare earth orthoferrites (E. D.lfiolb et al.,.l.. ippl. Phys. 39, 1362434).

It is, of course, desirable to measure and control the pressure withinthe vessel during these physical or chemical changes, either to controlthe changes, to determine what pressures produce particular observedchanges, or to maintain the pressure within safe limits. When anoncorrosive solution is employed, it is possible to measure thepressure within a pressure vessel with a pressure gauge which is eitherdirectly upon the vessel or physically removed from the vessel andconnected by means of a pressure line. It is undesirable, however, toallow corrosive materials to come into contact with the pressure gauge,since the gauge could be destroyed by the corrosive materials. The useof pressure lines is only a partial solution to the problem, since thecorrosive material may eventually reach the pressure gauge. Furthermore,the existence of pressure lines containing highly pressurized corrosivematerials presents an ever-present hazard, since even a slight leakanywhere in the system would release the corrosive material, possiblyresulting in considerable damage.

It is, therefore, an object of this invention to provide a process andapparatus for the measurement of pressure of a corrosive material, whilemaintaining the corrosive material within its pressure vessel.

SUMMARY OF Til-IE INVENTION These and other objects are accomplishedaccording to the present invention with an apparatus for subjecting acorrosive material to a controlled pressure comprising a pressurevessel, lined with a material which is resistant to attack by thecorrosive material to be subjected to pressure, and having a mouth forthe insertion and removal of corrosive material; and provided with apressure measurement chamber adjacent to the pressure vessel mouth,separated from the vessel by a flexible pressure-transmitting vesseldiaphragm. The diaphragm covers the vessel mouth, thereby preventing theescape of corrosive material from the vessel, and simultaneouslytransmits pressure to the pressure measurement chamber. The pressurewithin the pressure measurement chamber is then determined and taken asa measure of the pressure within the vessel itself.

The diaphragm must remain in a pressure-transmissive position duringthis process. This can be accomplished in at least two ways. First, anelectrical lead can be provided within the pressure measurement chamber,positioned so as to contact the vessel diaphragm upon the approach ofthe vessel diaphragm into the pressure measurement chamber; or a systemof valves can be used to ascertain the pressure-transmissive position ofthe vessel diaphragn.

Using the first method, an electrical lead is positioned such that thevessel diaphragm makes contact with the lead whenever the diaphragmapproaches into the pressure measure ment chamber. This contact isdetected electrically, and whenever contact is detected between the leadand the diaphragm pressure is increased within the pressure measurementchamber until contact between the lead and the diaphragm is broken. Ifit is suspected that the pressure within the pressure measurementchamber is greater than that within the pressure vessel, the pressurewithin the pressure measurement chamber can be decreased until contactis detected, and

then increased slightly until contact is broken. This insures that thediaphragm is in a pressure-transmissive position, so that the pressurewithin the pressure measurement chamber approximates that within thepressure vessel.

Using the second method, a system. of valves is used for periodicallyslightly altering the pressure within the pressure measurement chamberin order to flex; the vessel diaphragm and thereby detect any pressuredisparity between the pressure vessel and the pressure measurementchamber. Whenever such a disparity is detected the pressure within thepressure measurement chamber is altered, either by increasing ordecreasing the pressure, so that the disparity no longer exists. Thepressure within the pressure measurement chamber can then again be takenas a measure of the pressure within the pressure vessel itself.

BRIEF DESCRlPTlON OF THE DRAWINGS FIG. l is a sectional view of apressure vessel for use in the present invention.

FIG. 2 is an expanded sectional partial view of the vessel of FlG. llillustrating a first preferred embodiment of the present invention.

F116. 35 is a second expanded partial view of the vessel of FIG. ll,partially in section and illustrating a second preferred embodiment ofthe present invention.

DETAILED DESCRIP'TJION The present invention can be easily understood byreference to the drawings. In HO. 1, a sectional view of a pressurevessel according to the present invention is illustrated. Vessel housing1 1, preferably constructed of a sturdy material such as stainlesssteel, is lined with a material 12 which is resistant to attack by thecorrosive material to be subjected to pressure. The mouth 13 is coveredwith a flexible pressuretransmitting vessel diaphragm it. Both thelining material 12 and at least the exposed surface of the vesseldiaphragm M must be of a material which is resistant to attack by thecorrosive material to be subjected to pressure. It is preferred that theentire vessel diaphragm M be of a single material, e.g., silver.However, depending on the corrosive material to be studied, variousother solid noble metals, e.g., palladium, iridium, rhodium, ruthenium,osmium, gold or platinum can be used for the vessel lining anddiaphragm. Other materials which are inert under the conditions of usecan also be used. Vessel diaphragm M is held in place by plunger l5which is in turn held down by sealing gasket in, backup gasket l7,thrust washer l8 and capnut 19. Additional stability is obtained byusing a washer 20 held in place by a nut 21.

EXAMPLE ll Referring now to FIG. 2, a first preferred embodiment of thepresent invention is illustrated. Plunger 15 is provided with anelectrical lead 26 which is supported within plunger l5 by support means27 and 28 which electrically insulate lead 26 from plunger 15 but whichallow the passage of a pressuretransmitting fluid. The space 29 withinplunger l5 constitutes a portion of a pressure measurement chamber. Theend 3b of plunger is connected by means of a pressure line (not shown)to a distant pressure gauge (also not shown). The pressure within thepressure measurement chamber is then determined and taken as thepressure within the pressure vessel itself. This represents an accurateassessment of the pressure within the vessel, however, only so long asdiaphragm id remains in a pressure-transmissive position. In otherwords, if the pressure within the pressure vessel becomes so great as topush diaphragm 11d up within the space 29 within plunger l5 so thatfurther flexing is impossible, no further pressure would be transmittedby diaphragm M to the pressure measurement chamber.

In order to insure that diaphragm Ml remains in such apressure-transmissive position, according to this embodiment of thepresent invention, lead 26 is provided. Whenever the pressure within thepressure chamber increases, causing diaphragm 14 to approach into thepressure measurement chamber, contact is made between lead 26 anddiaphragm 14. A second electrical lead 31, connected via vessel housing11 and lining 12 to diaphragm 14, is provided. Whenever the circuitbetween lead 26 and lead 31 is closed, pressure within the pressuremeasurement chamber is increased. This process is continued until thecircuit is broken by the flexing of diaphragm 14 away from electricallead 26. This process can be repeated indefinitely. If it is suspectedthat the pressure within the pressure vessel is less than the pressurewithin the pressure measurement chamber, it is always possible torelease a slight amount of pressure within the pressure measurementchamber until contact between lead 26 and diaphragm 14 is accomplished.The pressure within the pressure measurement chamber can then beincreased until diaphragm l4 breaks contact with lead 26. Thus it isalways easy to insure that diaphragm 14 is relatively close to lead 26,but not touching, and therefore in a flexible, pressure-transmissiveposition.

EXAMPLE ll Referring now to FIG 3, a second preferred embodiment of thepresent invention is illustrated. In this case, no electrical leads arerequired. Plunger is connected by means of nut 41 and pressure line 42to a first valve 43. Next, pressure line 42 is connected to pressuregauge 44 and further to a second valve 45. The end 46 of pressure line42 past the second valve 45 is connected to a pump (not shown).Ordinarily, valve 43 is open and valve 45 is closed. When it is desiredto determine if the pressure within the pressure measurement chamber isthe same as the pressure within the pressure vessel itself, valve 43 isclosed, valve 45 is opened and the pump is activated to increase thepressure shown on gauge 44. For example, if the pressure shown on thegauge is on the order of 500-2000 atmospheres, the pressure should beincreased on the order of 1,000 psi. Then valve 45 is closed and valve43 is opened. This action will flex diaphragm 14 slightly and if thecorrect pressure is indicated then the gauge reading will return toalmost the original value. If, however, diaphragm 14 had been pushed upwithin plunger 15 so that diaphragm 14 were no longer pressuretransmissive, allowing the pressure within the pressure vessel to becomegreater than the pressure within the pressure measurement chamber, thana net increase in pressure at gauge 44 would be observed. It would thenbe necessary to repeat the valve opening and closing process as outlinedabove until substantially equal pressures at gauge 44 were obtained ontwo successive readings. This would indicate that diaphragm 14 had beendislodged from its position up within plunger 15, and was again flexibleand pressure transmissive.

We claim:

1. Apparatus for subjecting a corrosive material to a controlledpressure and measuring the pressure thereof, comprismg:

l. a pressure vessel, lined with a material which is resistant to attackby the corrosive material to be subjected to pressure, and having amouth for the insertion and removal of corrosive material;

2. a pressure measurement chamber detachably connected to the pressurevessel mouth, separated from the vessel y;

3. a flexible, pressure-transmitting vessel diaphragm, having a surfacewhich is resistant to attack by the corrosive material to be subjectedto pressure,

a. covering the vessel mouth, whereby to prevent the escape of corrosivematerial therefrom, and

b. transmitting pressure to the pressure measurement chamber;

4. means for measuring the pressure within the pressure measurementchamber; and

5. means for maintaining the vessel diaphragm in a pressuretransmissiveposition comprising:

a. an electrical lead within the pressure measurement chamber,positioned so as to contact the vessel diaphragm upon the approach ofthe vessel diaphragm into the pressure measurement chamber;

b. means for detection of contact between the electrical lead and thevessel diaphragm; and

c. means for increasing pressure within the pressure measurementchamber.

2. Apparatus according to claim 1, wherein the means for increasingpressure includes a means for repeatedly increasing the pressure withinthe pressure measurement chamber.

3. A process for measuring the pressure of a corrosive materialcomprising:

1. enclosing the corrosive material within a pressure vessel lined witha material which is resistant to attack by the corrosive material to besubjected to pressure, the vessel having a mouth for the insertion andremoval of corrosive material;

2. covering the vessel mouth with a flexible, pressure-transmittingvessel diaphragm, whereby to prevent the escape of corrosive materialtherefrom;

3. providing a pressure measurement chamber adjacent the pressure vesselmouth, the vessel diaphragm transmitting pressure to the pressuremeasurement chamber; and

4. measuring the pressure within the pressure measurement chamber; saidflexible, pressure-transmitting vessel diaphragm being maintained in apressure-transmitting position by:

a. providing an electrical lead within the pressure measurement chamber,positioned so as to contact the vessel diaphragm upon the approach ofthe vessel diaphragm into the pressure measurement chamber;

b. detecting any contact between the electrical lead and the vesseldiaphragm; and

c. upon detecting any contact between the lead and the diaphragm,increasing pressure within the pressure measurement chamber untilcontact between the lead and the diaphragm is broken.

1. Apparatus for subjecting a corrosive material to a controlledpressure and measuring the pressure thereof, comprising:
 1. a pressurevessel, lined with a material which is resistant to attack by thecorrosive material to be subjected to pressure, and having a mouth forthe insertion and removal of corrosive material;
 2. a pressuremeasurement chamber detachably connected to the pressure vessel mouth,separated from the vessel by;
 3. a flexible, pressure-transmittingvessel diaphragm, having a surface which is resistant to attack by thecorrosive material to be subjected to pressure, a. covering the vesselmouth, whereby to prevent the escape of corrosive material therefrom,and b. transmitting pressure to the pressure measurement chamber; 4.means for measuring the pressure within the pressure measurementchamber; and
 5. means for maintaining the vessel diaphragm in apressuretransmissive position, comprising: a. an electrical lead withinthe pressure measurement chamber, positioned so as to contact the vesseldiaphragm upon the approach of the vessel diaphragm into the pressuremeasurement chamber; b. means for detection of contact between theelectrical lead and the vessel diaphragm; and c. means for increasingpressure within the pressure measurement chamber.
 2. a pressuremeasurement chamber detachably connected to the pressure vessel mouth,separated from the vessel by;
 2. Apparatus according to claim 1, whereinthe means for increasing pressure includes a means for repeatedlyincreasing the pressure within the pressure measurement chamber. 2.covering the vessel mouth with a flexible, pressure-transmitting vesseldiaphragm, whereby to prevent the escape of corrosive materialtherefrom;
 3. providing a pressure measurement chamber adjacent thepressure vessel mouth, the vessel diaphragm transmitting pressure to thepressure measurement chamber; and
 3. A process for measuring thepressure of a corrosive material comprising:
 3. a flexible,pressure-transmitting vessel diaphragm, having a surface which isresistant to attack by the corrosive material to be subjected topressure, a. covering the vessel mouth, whereby to prevent the escape ofcorrosive material therefrom, and b. transmitting pressure to thepressure measurement chamber;
 4. means for measuring the pressure withinthe pressure measurement chamber; and
 4. measuring the pressure withinthe pressure measurement chamber; said flexible, pressure-transmittingvessel diaphragm being maintained in a pressure-transmitting positionby: a. providing an electrical lead within the pressure measurementchamber, positioned so as to contact the vessel diaphragm upon theapproach of the vessel diaphragm into the pressure measurement chamber;b. detecting any contact between the electrical lead and the vesseldiaphragm; and c. upon detecting any contact between the lead and thediaphragm, increasing pressure within the pressure measurement chamberuntil contact between the lead and the diaphragm is broken.
 5. means formaintaining the vessel diaphragm in a pressure-transmissive position,comprising: a. an electrical lead within the pressure measurementchamber, positioned so as to contact the vessel diaphragm upon theapproach of the vessel diaphragm into the pressure measurement chamber;b. means for detection of contact between the electrical lead and thevessel diaphragm; and c. means for increasing pressure within thepressure measurement chamber.